1. Field of Invention
The present invention relates to a method and system for confirmation in speech processing and systems incorporating the method. More specifically, the present invention relates to a method and system of random confirmation in speech processing and the systems incorporating the random confirmation method.
2. Discussion of Related Art
The need for automated speech system is growing because of the demand for quality service and the high cost of maintaining a quality service. For example, many companies provide call centers. Such call centers serve as an essential interface between a service provider and its customers through which customers may dial in for services or questions related to services offered by the companies. It is costly to maintain such call centers. It is desirable to automate some of the functionalities of a call center to reduce cost. For example, deploying an automated dialogue system to interact with a customer may significantly reduce the cost in both personnel cost and physical space cost. In such dialogue systems, confirmation is sometimes conducted to improve quality.
FIG. 1(a) (Prior Art) illustrates a conventional speech system 100 with a deterministic confirmation mechanism. The conventional speech system (with confirmation capability) 100 comprises a speech recognition mechanism 110, a deterministic confirmation decision mechanism 120 which makes a deterministic confirmation decision based on a pre-determined confirmation range of scores 125, and a confirmation mechanism 130 that carries out a confirmation based on the confirmation decision made by the deterministic confirmation decision mechanism 120. The speech recognition mechanism 110 interacts with a user 105 and processes the speech of the user. The speech recognition mechanism 110 may produce words recognized with associated confidence scores indicating the level of confidence that the speech recognition mechanism 110 has in the recognition results.
Based on the confidence score, the deterministic confirmation decision mechanism 120 may decide that a confirmation is required. In this case, a confirmation activation signal 140 is generated to activate the confirmation mechanism 130 to carry out the confirmation. In other situations, the deterministic confirmation decision mechanism 120 may decide that there is no confirmation needed and generate a no confirmation signal 145 to inform a routing mechanism 150 to route the underlying call. A “no confirmation” decision may be reached when either the confidence score indicates a high confidence in the recognition result or the confidence score is too low to carry out a confirmation. If there is a high confidence, the routing mechanism 150 may trigger an automatic response mechanism 170 to respond the user's inquiry. For example, based on the recognition result which corresponds to an inquiry, a pre-stored response may be retrieved from a database as an automated answer to the inquiry. On the other hand, in case of a very low confidence score, the routing mechanism 150 may route the call to a human operator 160 to handle the inquiry.
In a deterministic confirmation scheme, when a confidence score associated with a speech recognition result is within a pre-determined range, a confirmation is performed with the user. FIG. 1(b) (Prior Art) illustrates such a deterministic confirmation range. The X-axis in FIG. 1(b) represents the value of a confidence score 175. A confidence score may be within a range between the value 0 and an upper limit max. Within the range of [0, max], it may be further divided into different regions, within each of which different operations may be carried out. For example, a deterministic confirmation range 190 may be defined through a low threshold 180 corresponding to a particular confidence score value and a high threshold 15 corresponding to a higher confidence score value. Under a deterministic confirmation scheme, a speech recognition result with confidence score falling within the deterministic conformation range 190 may need to be confirmed.
The range [0, low threshold 180) may be defined as a rejection range 192 and the range (high threshold 185, max] may be defined as an acceptance range 195. A speech recognition result with a confidence score below the low threshold 180 may be rejected (too low confidence). A speech recognition result with a confidence score exceeding the high threshold 185 may be accepted without confirmation.
In a deterministic confirmation scheme, a speech recognition result from either the rejection range or the acceptance range is not confirmed. Although a speech recognition result with a confidence score that is lower than the low threshold 180 may be rejected, it may still be a correct recognition. On the other hand, a speech recognition result with a confidence score that is higher than the high threshold 185, although accepted, may still be in error. Without confirmation on the speech recognition results within these regions, it may be difficult to assess the performance of the underlying speech system.